The expansion of the Universe is speeding up – proving once again that
Einstein's theory of relativity is correct - according to astronomers who
studied hundreds of thousands of galaxies.

In the biggest survey ever conducted using the Hubble Space telescope, 446,000 galaxies were studied to see how matter was distributed throughout the universe and how quickly it had expanded.

And the astronomers found that the universe was growing faster and faster with time, as predicted by Einstein in his theory of general relativity.

Scientists claim that the universe is made up of three different components – normal matter, which is the physical objects in the universe such as the planets – dark matter, which is invisible matter that creates the gravitational pull that causes galaxies to form – and an unknown energy referred to as "dark energy", the force which causes the universe to expand.

Einstein's theory of general relativity claims that space and time are a geometrical structure which can be changed by the behaviour of the matter inside it.

So proof that the expansion of the universe is speeding up shows that the contents of the universe, such as the "dark energy" causing it to inflate, are influencing its structure.

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Ludovic Van Waerbeke, of the Department of Physics and Astronomy at Leiden University in the Netherlands, said: "Our results confirmed that there is an unknown source of energy in the universe which is causing the cosmic expansion to speed up, stretching the dark matter further apart exactly as predicted by Einstein's theory.

"The data from our study are consistent with these predictions and show no deviation from Einstein's theories."

Mr Van Waerbeke pioneered a technique to measure the invisible web of dark matter which was used in the study.

In a method similar to taking an X-ray of the body to reveal the underlying skeleton, the technique, known as weak gravitational lensing, allows astronomers to see how light from distant galaxies is bent and distorted by the dark matter as it travels towards earth.

They can then map the dark matter structures, which make up 80 per cent of the universe.

The study leader Tim Schrabback said: "What we tested is how the structure of the universe grows with time. If the universe expands then the gravitational lensing changes because the distance between the objects has changed.

"I think from that perspective this is quite exciting because this is the first time this measurement has been done with weak gravitational lensing alone. Before it's always been done with other measurements because the lensing was not effective.

"The other thing that is really exciting is that in the next years there will be much larger surveys which will have more accurate measurements for dark energy and expansions, and we will see some very interesting results."

As well as this technique, astronomers in the study used the Cosmic Evolution Survey (COSMOS), a joint project by the European Space Agency and NASA involving over 100 scientists from a dozen countries.

For the survey, a camera aboard the Hubble telescope photographed 575 slightly overlapping views of the same part of the universe, which took nearly 1,000 hours of observation, during which the Hubble circled the earth nearly 600 hundred times.

Mr Schrabback said: "This is the largest survey ever done with the Hubble telescope. The images make up a large mosaic of the sky.

"The Hubble has a great advantage from images taken from earth because there is no blurring from the atmosphere."